Fuel composition containing heavy fraction

ABSTRACT

A fuel composition comprising: (a) a hydrocarbon fuel selected from the group consisting of diesel and gasoline; and (b) a synthetic blend, wherein the fuel composition further comprises a fuel additive composition comprising:  
     (1) an ethoxylated alcohol composition having the structure:  
                 
 
     wherein R 1  is a C 6 , C 7 , C 8 , C 9 , C 10 , C 11 , C 12 , C 13 , C 14 , C 15 , or C 16  hydrocarbon, R 2  is H or CH 3 , and x is 1-7;  
     (2) a polyethylene glycol ester composition having the structure:  
                 
 
     wherein R 3  is a C 11 , C 12 , C 13 , C 14 , C 15 , or C 16 , C 17 , C 18 , or C 19  hydrocarbon, R 4  is H or CH 3 , y is 1-20, R 5  is H or COR 3 ; and  
     (3) an alkanolamide composition having the following general structure:  
                 
 
     wherein R 6  is a C 12 , C 13 , C 14 , C 15 , or C 16 , C 17 , or C 18 , hydrocarbon, R 7  is H or CH 2 CH 2 OH.

BACKGROUND

[0001] In recent years, it has become more and more important to consider and control the emissions resulting from combustion processes, particularly from mobile combustion processes. Gasoline and diesel are the most prominent fuels used for mobile combustion sources. It has become apparent that the efficiency of a compression ignition engine is far better than a spark ignition engine. Among the emissions which must be controlled from mobile combustion sources are carbon monoxide (CO), carbon dioxide (CO₂), nitrogen oxides (NO_(x)), particulate matter (PM), and hydrocarbons (HC).

[0002] Diesel engines present a further problem for the automotive and transportation industry because the exhaust emissions from these type of engines typically include high levels of PM, together with NO_(x). Diesel engine particulate emissions are easily observable in the form of black smoke discharged from the engine. Currently, diesel engine particulate matter emissions can be controlled by the use of black smoke filters or catalytic converters. While these emission-control devices are effective in decreasing particulate matter emissions, they are not effective in reducing NO_(x) emissions. Attempts have been made to reduce NO_(x) and PM emissions from internal combustion engines. However, these known emission control systems and strategies have associated disadvantages.

[0003] Compression ignition engines have been trialled with various different fuels from varying feedstocks. In selecting a fuel composition, the effects of that composition a variety of factors must be considered and taken into account. Among these factors are engine performance (including efficiency, and emissions), cost of end product, necessary infrastructure changes to produce the components of the composition, and availability of feedstock to provide those components.

[0004] In different parts of the world incentives are available for cleaner burning fuels to replace “classic” diesel. In Europe the EN 590 spec diesel is characterised by an initial boiling point of 170° C. and a final boiling point of 590° C. The preferred sulfur content is less than 50 ppm. In the US there are, essentially, 2 different specs. An EPA spec and a CARB spec diesel with less than 500 ppm sulfur requirements. The difference in the 2 specifications is aromatic content and distillation boiling point ranges.

[0005] Over the next decade, it is expected that it will be desirable to even further decrease the amount of sulfur in diesel fuel. However, decreases in the sulfur content of the fuel generally results in a decrease in the lubricity of the fuel, which generally results in increased engine wear.

[0006] One possible alternative or supplement to ordinary diesel is biodiesel. Biodiesel is a nontoxic, biodegradable replacement for petroleum diesel which is made from vegetable oil, recycled cooking oil and tallow. Biodiesel belongs to a family of fatty acids called methyl esters which are defined by the medium length, C₁₆-C₁₈ fatty acid linked chains. These linked chains help differentiate biodiesel from regular petroleum diesel. Biodiesel has similar performance characteristics as ordinary, petroleum-based diesel, but is cleaner burning.

[0007] Mixtures of biodiesel and petroleum-based diesel are able to reduce particle, hydrocarbon, and carbon monoxide emissions, as compared with ordinary diesel. Direct benefits associated with the use of biodiesel, in a 20% blend with ordinary diesel, as opposed to using straight diesel, include increasing the fuel's cetane and lubricity for improved engine life and reducing the fuel's emissions profile for CO, CO₂, PM, and HC.

[0008] However, biodiesel is expensive to manufacture, and does not help reduce NO_(x) emissions. Some biodiesels, in fact, exacerbate NO_(x) emissions. To alleviate this problem there is are government incentives available for the utilisation of B20. B20 is a blend comprising 20% biodiesel and 80% diesel. Users of such fuels can take advantage of a portion of the incentives made available to users of renewable fuels. Specifically, the use of 5 gallons of B20 fuel is equivalent to the use of 1 gallon of renewable fuel. It would be useful to be able to generate a fuel composition which would be able to take full advantage of the available incentives, instead of the ⅕th incentive currently available for use of B20.

OBJECTS OF THE INVENTION

[0009] It is a purpose of this invention to show that it is possible to adhere to the responsibility of carbon dioxide control without major new capital expenditures and infrastructure changes in storage, refining or distribution of fuel.

[0010] It is a further purpose of this invention to provide a solution to the above-problems and use feedstocks which are currently available through the existing refinery and distribution infrastructures.

[0011] It is a further purpose of the invention to show that biodiesel can be used in fuel compositions and its NO_(x) disadvantage can be corrected, while allowing the user to take full advantage of available incentives for use of renewable fuels.

[0012] A further purpose of the invention is to provide a method for improving fuel efficiency and reducing NO_(x) emissions in engines operated at average ambient temperatures above 0° C.

DESCRIPTION OF THE INVENTION

[0013] These and other purposes are achieved by creating fuel compositions utilising a mix of petroleum-derived diesel with a heavy fraction fuel derived from natural gas (hereinafter called “synthetic blend”), which is not “from the barrel” (i.e. derived from crude oil). In one aspect of the invention, the heavy fraction fuel can be derived from petroleum.

[0014] As used in this application, the term “synthetic blend” means a heavy fraction fuel not derived from petroleum. In a preferred embodiment, the heavy fraction fuel is derived from natural gas condensate. In an alternative embodiment, the heavy fraction fuel is obtained from natural gas via a gas-to-liquid process, in which the gas is converted into a waxy material, and subsequently converted into a liquid. By “heavy fraction fuel,” what is meant is C₅-C₂₀ hydrocarbon fuel. In one aspect, the heavy fraction fuel is a C₈-C₂₀ hydrocarbon fuel. The preferred synthetic blend is derived by straight fractionation from natural gas condensate. Preferably, the synthetic blend has an initial boiling point ranging from about 120° C. to 160° C., more preferably from about 130° C. to 150° C., most preferably 140° C., and a final boiling point ranging from about 290° C. to 330° C., more preferably from about 300° C. to 320° C., most preferably 310° C. The synthetic blend will normally have a high cetane value, low aromatic content, low sulfur content, and poor lubricity.

[0015] In order to take advantage of the synthetic blend, those skilled in the art must create blends from and within the existing diesel criteria to enable the complete fuel to have an initial boiling point greater than the desired standard minimum (for instance over 170° C. for EN 590).

[0016] Ordinarily, the synthetic blend will make up from 5-95% of the final fuel composition, preferably from 5% to 40%, more preferably from 15-25%, most preferably 20%.

[0017] Unless otherwise noted, all relative percentages described in this application are by weight.

[0018] In certain circumstances, however, it may be viable, necessary, or desirable to create an “Epact fuel,” which is a regulatory designation for fuels which are derived from renewable sources (including synthetic blends from natural gas sources), the renewable sources content being greater than the petroleum-based components. Extensive use of Epact fuels have been hampered by a number of factors, including the fact that they have a boutique status. This means that feedstocks for Epact fuels are limited, which means that widespread use will require extensive new infrastructure.

[0019] The present invention addresses the shortage of feedstocks and the fact of low sulfur causing lubricity problems and also, succeeding with an Epact fuel by blending a combination of biodiesel, synthetic blend, and regular diesel. The result would be a high lubricity, high cetane fuel. However certain bio-diesel blends have been known to create extra NO_(x) emissions.

[0020] It has been found that these problems can be alleviated through the use of a fuel additive composition described in International Patent Application No. WO 01/38464, the disclosure of which is hereby incorporated by reference. The fuel additive composition comprises the following three components:

[0021] (1) an ethoxylated alcohol composition having the following general structure:

[0022] wherein R¹ is a C₆, C₇, C₈, C₉, C₁₀, C₁₁, C₁₂, C₁₃, C₁₄, C₁₅, or C₁₆ hydrocarbon, R² is H or CH₃, and x is 1-7. It is preferred that R¹ is C₉ or C₁₀ and x is 2.5. Preferably, the additive contains from about 20 to 80% of the ethoxylated alcohol. More preferably, the additive includes from about 33 to 55% of the ethoxylated alcohol constituent;

[0023] (2) a polyethylene glycol ester composition having the following general structure:

[0024] wherein R³ is a C₁₁, C₁₂, C₁₃, C₁₄, C₁₅, or C₁₆, C₁₇, C₁₈, or C₁₉ hydrocarbon, R⁴ is H or CH₃, y is 1-20, R⁵ is H or COR³. Preferably, R³ is C₁₇ and R⁵ is COR. Polyethylene glycol diesters of oleic acid are preferred, as are polyethylene glycol ditallates. The use of the mono-oleates is also possible. The preferred polyethylene glycol ester may include blends of different compounds. Preferred forms of the additive include from about 10 to 60%, and more preferably from about 25 to 40%, of the polyethylene glycol ester constituent. More highly preferred embodiments comprise from about 25 to 33% of the polyethylene glycol ester constituent;

[0025] (3) an alkanolamide composition having the following general structure:

[0026] wherein R⁶ is a C₁₂, C₁₃, C₁₄, C₁₅, or C₁₆, C₁₇, or C₁₈, hydrocarbon, R⁷ is H or CH₂CH₂OH. Preferably, R⁶ is C₁₇ and R⁷ is CH₂CH₂OH. Oleic acid diethanolamides are highly preferred alkanolamides for use in practicing the invention. The ethanolamide constituent may be provided as a blend of different ethanolamides. Preferred forms of the additive include from about 10 to 60%, more preferably from about 25 to 40% by weight of the alkanolamide. More preferred is an additive containing from about 25 to 33% of the alkanolamide constituent.

[0027] Optionally, the fuel additive can contain a nitrogen-containing component selected from the group consisting of urea, cyanuric acid, triazine, ammonia, and mixtures thereof. Ordinarily, when present, the nitrogen-containing compound is present in an amount from about 3% to 35% with respect to the fuel additive composition, more preferably from about 3 to 32%, most preferably from about 10% to 32%.

[0028] As used throughout the specification and claims, terms such as “between 6 and 16 carbon atoms,” “C₆” and “C₆₋₁₆” are used to designate carbon atom chains of varying lengths within the range and to indicate that various conformations are acceptable including branched, cyclic and linear conformations. The terms are further intended to designate that various degrees of saturation are acceptable. Moreover, it is readily known to those of skill in the art that designation of a constituent as including, for example, “C₁₇” or “2.5 moles of ethoxylation” means that the constituent has a distribution with the major fraction at the stated range and, therefore, such a designation does not exclude the possibility that other species exist within the distribution. The constituents of this invention may be isolated or present within a mixture and remain within the scope of the invention.

[0029] The fuel additive preferably comprises from about 30% to 75% of the ethoxylated alcohol, and more preferably comprises from about 33-55% of this constituent. Ethoxylated alcohols can be prepared by the alkoxylation of linear or branched alcohols with commercially available alkaline oxides, such a ethylene oxide (“EO”) or propylene oxide (“PO”), or mixtures thereof.

[0030] Ethoxylated alcohols suitable for use in the invention are available from Tomah Products, Inc. of 337 Vincent Street, Milton, Wis. 53563 under the trade name of Tomadol™. Illustrative Tomadol products include Tomadol 91-2.5 and Tomadol™ 1-3. Tomadol™ 91-2.5 is a mixture of C9, C10, and C11 alcohols with an average of 2.7 moles of ethylene oxide per mole of alcohol. The HLB value (Hydrophyllic/Lipophyllic Balance) of Tomadol™ 91-2.5 is reported as 8.5. Tomadol™ 1-3 is an ethoxylated C11 (major proportion) alcohol with an average of 3 moles of ethylene oxide per mole of alcohol. The HLB value is reported as 8.7.

[0031] Other sources of ethoxylated alcohols include Huntsman Corp., Salt Lake City, Utah, Condea Vista Company, Houston, Tex., and Rhodia, Inc., Cranbury, N.J.

[0032] The fuel additive preferably comprises from about 10 to 60% by weight of the polyethylene glycol ester constituent. More preferred forms of the fuel additive include from about 25% to 40% by weight of the polyethylene glycol ester constituent while still more preferred embodiments comprise from about 25% to 33% by weight of the polyethylene glycol ester constituent. The monoester can be manufactured through the alkoxylation of a fatty acid (such as oleic acid, linoleic acid, coco fatty acid, etc.) with EO, PO, or mixtures thereof. The diesters can be prepared by the reaction of a polyethylene glycol with 2 equivalents of a fatty acid.

[0033] Preferred polyethylene glycol esters are PEG 400 dioleate, which is available from Lambent Technologies Inc. of Skokie, Ill., as Lumulse 42-0, and PEG 600 dioleate, also available from Lambent as Lumulse 62-O. Another polyethylene glycol ester suitable for use in the invention includes Mapeg brand 600-DOT, Polyethylene glycol 600 distallate from BASF Corporation, Speciality Chemicals, Mt. Olive, N.J. Other suppliers of these and related chemicals are Stepan Co., Lonza, Inc. and Goldschmidt, AG of Hopewell, Va.

[0034] The fuel additive comprises form about 10% to 60% by weight of the alkanolamide constituent. More preferred forms of the fuel additive include from about 25% to 40% by weight of the alkanolamide constituent while still more preferred embodiments comprise from about 20% to 80% by weight of the alkanolamide constituent. Generally, the alkanolamides can be prepared by reacting a mono- or diethanolamide with a fatty acid ester.

[0035] A preferred alkanolamide is oleic diethanolamide. Alkanolamides suitable for use in the invention are available from McIntyre Group, University Park, Ill. under the trade name of Mackamide. One example is Mackamide MO, “Oleamide DEA.” Henkel Canada is another commercial source of suitable alkanolamides such as Comperlan OD, “Oleamide DEA.” Other commercial sources of alkanolamides are Rhodia, Inc. and Goldschmidt AG.

[0036] The components of fuel additive can mixed in any order using conventional mixing devices. Ordinarily, the mixing will be done at ambient temperatures, from about 0° C. to 35° C. Normally, the fuel additive can be splash blended into the base fuel. Ideally, the fuel additive will be a homogeneous mixture of each of its components.

[0037] Another preferred fuel composition of the invention comprises a 50/50 blend of regular diesel with a synthetic blend. This has cost advantages over biodiesel blends, qualifies for Epact status, and is cheaper than CARB diesel to produce because the diesel component is EPA 2 diesel, not the premium CARB blend. Particulate and NO_(x) emissions and are reduced but so is CO₂, both directly by an increase in miles per gallon obtained when using the fuel composition, and indirectly since over 50% of the fuel is deemed to be from a renewable source.

[0038] Preferably, the fuel composition will comprise from about 0.01 to 3% of the fuel additive composition.

[0039] Fuel compositions according to the invention can also comprise an oxygenated component selected from the group consisting of ethanol, methanol, ethylal (dethoxyethane) and methylal (dimethoxymethane). The fuel compositions can also comprise a cetane improver. Cetane improvers, such as ethyl hexyl nitrate and octyl nitrate, increase the cetane value of diesel fuel, and are compounds well known in the art.

[0040] It is also within the scope of this invention to provide a method of increasing the efficiency of a diesel-based fuel and decreasing the NO_(x) emissions from engines using such fuels, comprising the use of a fuel composition comprising: (a) diesel; and (b) a heavy fraction, from any source) in an engine which is being operated at average ambient temperatures of at least 0° C., preferably at average ambient temperatures of at least 5° C., more preferably at average ambient temperatures of at least 10° C., most preferably at average ambient temperatures of at least 15° C. The amount of heavy fraction in the fuel composition can range from about 30% to 80%, more preferably from about 45% to 60%, most preferably from about 50% to 60%.

EXAMPLES

[0041] The following examples are intended to illustrate, but not in any way limit, the invention. Various blends were made to compare the characteristics of the various blends of fuel with performance in emissions and fuel efficiency (i.e., miles per gallon, or mpg). Surprisingly, the properties of the fuels blends did not conform to industry beliefs and findings. In general, cetane levels were around and above the CARB equivalent fuel. Lubricity was improved when either the fuel additive and the bio-diesel were used in the fuel blend, or the additive was used alone. The aromatic content of a fuel is normally associated with its NO_(x) and particulate emissions; higher aromatic content generally correlating with increased emissions and generating a lower cetane number.

[0042] The synthetic blend used in each of the exemplified fuel compositions was obtained from a natural gas condensate. Such products are available from numerous sources, including ExxonMobil and Phillips Petroleum. The physical properties of the synthetic blend, and its component analysis, along with those of the biodiesel blends used in the examples, are provided in Table 1 below. The soy oil biodiesel was obtained from Griffin Industries, of Kentucky. The yellow grease biodiesel was also obtained from Griffin Industries. The testing methods for the various measurements are identified by ASTM method number in the table. The same tests were also run on the final fuel blends, the results of which are reported in Tables 2 and 3.

[0043] Emissions testing was conducted on, a 1991 Detroit Diesel Series 60 diesel engine was tested according to the Code of Federal Regulations Title 40 subsection 86 by The Southwest Research Institute. Department of Emissions, San Antonio Tex.

[0044] The carbon content of fuel blends, which correlates with density, is related to power torque and miles per gallon (mpg) which can be obtained with the fuel blend. Generally, it is expected that a denser fuel will deliver more mpg. Density is also related to the distillation parameters of the fuel; the lighter the fraction, the quicker it boils off and the less mileage is expected.

[0045] Each of the fuel blends is described below. The results are summarized in Tables 2, 3, and 4. Table 2 shows the physical properties of the blends, including cetane numbers, lubricities, and component analyses. Table 3 shows elemental analysis and distillation parameters for each fuel blend. Table 4 shows the emissions characteristics of the fuel blends.

[0046] The D2 baseline fuel used in each example was a typical EPA No. 2 diesel fuel, obtained from the Southwest Research Institute. The CARB-equivalent fuel was also obtained from Southwest Research Institute.

[0047] The fuel additive used for each blend contained 33.3% Tomadol™ 91-2.5, 33.3% oleic diethanolamide and 33.3% PEG 400 dioleate.

[0048] Unless otherwise noted, all of the compositions were made by splash blending the components.

[0049] Fuel J ½

[0050] Fuel J 1/2 contained 79.5% of the D2 baseline fuel, 20% of the synthetic blend, and 0.5% of the fuel additive. The carbon weight was slightly less than the D2 baseline fuel. The distillation curve was also premature when compared to D2. This suggests that Fuel J ½ was less dense than the D2 fuel.

[0051] NO_(x) and particulate emissions were reduced and an increase in mpg was recorded.

[0052] Fuel K1 ½

[0053] Fuel K1 ½ contained 48.8% of the D2 baseline fuel, 31% of the synthetic blend, 20% soy biodiesel, and 0.2% of the fuel additive. Fuel K1 ½ had a lower percentage of carbon, good lubricity and oxygen content. The fuel composition is a B20 blend which does not show an increase in NO_(x) emissions and shows a substantial decrease in particulate emissions.

[0054] Fuel K2 ½

[0055] Fuel K2 ½ contained 48.8% of the D2 baseline fuel, 31% of the synthetic blend, 20% yellow grease biodiesel, and 0.2% of the fuel additive. Fuel K2 ½ had a lower percentage of carbon, good lubricity and oxygen content. The fuel composition is a B20 blend which does not show an increase in NO_(x) emissions and shows a substantial decrease in particulate emissions.

[0056] Fuel K3 ½

[0057] Fuel K3 ½ contained 33.2% of the D2 baseline fuel, 33.2% of the synthetic blend, 33.1% soy biodiesel, and 0.5% of the fuel additive. Fuel K3 ½ had a lower percentage of carbon, good lubricity and oxygen content. The fuel composition is a B20 blend which does not show an increase in NO_(x) emissions and shows a substantial decrease in particulate emissions of over 30%.

[0058] Fuel O

[0059] Fuel O contained 50.1%% of the D2 baseline fuel, 49.4% of the synthetic blend, and 0.5% of the fuel additive. Fuel O had a lower percentage of carbon when compared to the base fuels, and showed good lubricity. Even with an aromatic content within one percent of the CARB equivalent fuel and with almost 200 times more sulfur there was a 14% reduction in particulate emissions. The distillation parameters of Fuel O suggests a less dense fuel than the base fuels. Nevertheless, Brake Specific Fuel Consumption was improved by 6%.

[0060] Therefore, it can be seen that, with the additive and these prescribed fuel blends it is possible to reduce particulate emissions, even with a higher aromatic content fuel, and gain reductions in NO_(x) emissions, even negate nox increases with the presence of a biodiesel component. In addition, MPG can be increased when compared to heavier fraction, more dense fuels. TABLE 1 Additive Type ASTM Yellow Measurement Method Soy Oil Grease Synthetic blend Physical Properties Cetane Number D613 ND ND   57.7 Lubricity, mm D6079 0.155 0.155     0.665 Lubricity, g D6078 >6000 >6000 1700  Component Analysis Sulfur, wt % D2622 <0.001 0.0012     0.0017 Aromatics, vol % D1319   UTP^(a) UTP   0^(b) Olefins, vol % D1319 UTP UTP   0^(b) Saturates, vol % D1319 UTP UTP 100 Distillation Parameters IBP, ° F. D86 614 612 345 10%, ° F. D86 626 626 366 50%, ° F. D86 630 632 393 90%, ° F. D86 660 656 455 EP, ° F. D86 664 664 496

[0061] TABLE 2 EM-4370-F EM-4371-F K2 1/2 EM-4374-F K1 1/2 48.8% D2 + K3 1/2 EM-4369-F 48.8% D2 + 31% synthetic 33% D2 + EM-4380-F EM-4155-F J 1/2 31% synthetic blend + 33% synthetic O EM-4191-F M 1/2 79.5% D2 + blend + 20% yellow blend + 50% D2 + L 2/3 CARB- 20% synthetic 20% soy grease bio- 33% soy 50% synthetic Measurement D2 Baseline Equiva- blend + bio-diesel + diesel + bio-diesel + blend + Test ref. fuel lent fuel 0.5% additive 0.2% additive 0.2% additive 0.5% additive 0.5% additive Physical Properties Cetane Number 47.4 53.5 51.6 52 53 51.3 53.5 Lubricity, mm 0.52 0.57 0.25 0.215 0.145 0.225 0.315 Lubricity, g 4100 2850 5300 >6000 5700 5900 >6000 Component Analysis Sulfur, wt % 0.043 <0.001 0.0284 0.0315 0.0186 0.0147 0.0197 Aromatics, vol % 31.9 20.6 26.3 15.57 15.57 10.53 19.2 Olefins, vol % 1.5 4.5 1 0.73 0.73 0.5 2.4 Saturates, vol % 66.6 74.9 72.7 63.5 63.5 54.98 78.4

[0062] TABLE 3 EM-4370-F EM-4371-F K2 1/2 EM-4374-F K1 1/2 48.8% D2 + K3 1/2 EM-4369-F 48.8% D2 + 31% synthetic 33% D2 + EM-4380-F J 1/2 31% synthetic blend + 33% synthetic O EM-4155-F 79.5% D2 + blend + 20% yellow blend + 50% D2 + EM-4191-F M 1/2 20% synthetic 20% soy grease bio- 33% soy 50% synthetic L 2/3 CARB- blend + bio-diesel + diesel + bio-diesel + blend + Measurement D2 Baseline Equivalent 0.5% additive 0.2% additive 0.2% additive 0.5% additive 0.5% additive Other, ppm NDb ND ND 20 20 33 ND Water, ppm ND ND ND ND ND 131 ND Elemental Analysis Carbon, wt % 86.73 86.37 85.45 84.32 83.96 82.82 85.79 Hydrogen, wt % 13.27 13.63 13.1 13.3 13.13 13.08 13.82 Oxygen, wt % ND ND 1.45 2.38 2.91 4.1 0.39 Nitrogen, wt % ND ND ND ND ND ND ND Distillation Parameters IBP, ° F. 352.3 346 349 348 347 352 343 10%, ° F. 423.1 384 387 385 381 384 375 50%, ° F. 514.9 477 485 503 499 524 450 90%, ° F. 599.3 604 585 627 625 635 571 EP, ° F. 642.7 658 633 650 651 653 624

[0063] TABLE 4 EM-4370-F EM-4371-F K2 1/2 EM-4374-F K1 1/2 48.8% D2 + K3 1/2 EM-4369-F 48.8% D2 + 31% synthetic 33% D2 + EM-4380-F J 1/2 31% synthetic blend + 33% synthetic O EM-4155-F 79.5% D2 + blend + 20% yellow blend + 50% D2 + EM-4191-F M 1/2 20% synthetic 20% soy grease bio- 33% soy 50% synthetic L 2/3 CARB- blend + bio-diesel + diesel + bio-diesel + blend + Measurement D2 Baseline Equivalent 0.5% additive 0.2% additive 0.2% additive 0.5% additive 0.5% additive BSHC g/hp hr 0.082 0.084 0.098 0.1 0.093 0.095 0.098 CO g/hp hr 2.603 2.332 2.435 2.199 2.174 2.154 2.06 Nox g/hp hr 4.8 4.407 4.715 4.785 4.705 4.8 4.28 PM g/hp hr 0.195 0.181 0.176 0.144 0.148 0.134 0.168 CO2 g/hp hr 563.8 555.5 548.6 548.2 548 547.9 524.3 BSFC g/hp hr 0.394 0.39 0.389 0.395 0.396 0.401 0.37 ^(against) CARB BSHC % 16.7 CO % −11.67 Nox % −2.82 PM % −7.2 CO2 % −5.6 BSFC % −5.13 Against EPA BSHC % 19.5 21.9 13.4 15.8 19.5 CO % −6.5 −15.6 −16.5 −17.25 −20.87 Nox % −1.7 −0.3 −1.99 0 −10.76 PM % −9.8 −26.2 −24.2 −32.8 −13.85 CO2 % −2.7 −2.8 −2.8 −2.83 −7.01 BSFC % −1.3 0.25 0.5 1.78 −6.1 

We claim:
 1. A fuel composition comprising: (a) a hydrocarbon fuel selected from the group consisting of diesel and gasoline; and (b) a synthetic blend.
 2. The fuel composition of claim 1, wherein the hydrocarbon fuel is diesel.
 3. The fuel composition according to claim 2, wherein the fuel composition further comprises a fuel additive composition comprising: (1) an ethoxylated alcohol composition having the structure:

wherein R¹ is a C₆, C₇, C₈, C₉, C₁₀, C₁₁, C₁₂, C₁₃, C₁₄, C₁₅, or C₁₆ hydrocarbon, R² is H or CH₃, and x is 1-7; (2) a polyethylene glycol ester composition having the structure:

wherein R³ is a C₁₁, C₁₂, C₁₃, C₁₄, C₁₅, or C₁₆, C₁₇, C₁₈, or C₁₉ hydrocarbon, R⁴ is H or CH₃, y is 1-20, R⁵ is H or COR³; and (3) an alkanolamide composition having the following general structure:

wherein R⁶ is a C₁₂, C₁₃, C₁₄, C₁₅, or C₁₆, C₁₇, or C₁₈, hydrocarbon, R⁷ is H or CH₂CH₂OH.
 4. The fuel composition according to claim 3, wherein the fuel additive further comprises a nitrogen-containing component selected from the group consisting of urea, cyanuric acid, triazine, ammonia, and mixtures thereof.
 5. The fuel composition according to claim 4, wherein the nitrogen containing component is urea.
 6. The fuel composition according to claim 3, wherein in the fuel additive, component (1) is present in an amount from about 30% to 75% with respect to the fuel additive, component (2) is present in an amount from about 10% to 60% with respect to the fuel additive, and component (3) is present in an amount from about 10% to 60% with respect to the fuel additive.
 7. A fuel composition comprising: (a) a hydrocarbon fuel selected from the group consisting of diesel and gasoline; (b) biodiesel; and (c) synthetic blend.
 8. The fuel composition of claim 7, wherein the hydrocarbon fuel is diesel
 9. The fuel composition according to claim 8, wherein the fuel composition further comprises a fuel additive composition comprising: (1) an ethoxylated alcohol composition having the structure:

wherein R¹ is a C₆, C₇, C₈, C₉, C₁₀, C₁₁, C₁₂, C₁₃, C₁₄, C₁₅, or C₁₆ hydrocarbon, R² is H or CH₃, and x is 1-7; (2) a polyethylene glycol ester composition having the structure:

wherein R³ is a C₁₁, C₁₂, C₁₃, C₁₄, C₁₅, or C₁₆, C₁₇, C₁₈, or C₁₉ hydrocarbon, R⁴ is H or CH₃, y is 1-20, R⁵ is H or COR³; and (3) an alkanolamide composition having the following general structure:

wherein R⁶ is a C₁₂, C₁₃, C₁₄, C₁₅, or C₁₆, C₁₇, or C₁₈, hydrocarbon, R⁷ is H or CH₂CH₂OH.
 10. The fuel composition according to claim 9, wherein the fuel additive further comprises a nitrogen-containing component selected from the group consisting of urea, cyanuric acid, triazine, ammonia, and mixtures thereof.
 11. The fuel composition according to claim 10, wherein the nitrogen-containing component is urea.
 12. The fuel composition according to claim 9, wherein in the fuel additive, component (1) is present in an amount from about 30% to 75% with respect to the fuel additive, component (2) is present in an amount from about 10% to 60% with respect to the fuel additive, and component (3) is present in an amount from about 10% to 60% with respect to the fuel additive.
 13. A method of increasing the efficiency of a diesel-based fuel and decreasing the NO_(x) emissions from engines using such fuels, comprising the use of a fuel composition comprising: (a) diesel; and (b) a heavy fraction; in an engine which is being operated at average ambient temperatures of at least 0° C.
 14. The fuel composition of claim 1, wherein the synthetic blend comprises natural gas condensate. 